[stouset]

> I'm not a lawyer.

> But I do believe there's reason to consider Apple's policy relative to iMessage clients monopolistic.

In order for antitrust laws to apply, it’s not enough to exhibit monopolistic behavior. You actually have to be a monopoly and use this behavior to achieve and/or retain it.

[tzs]

That's not the whole story in the United States. Antitrust law prohibits monopolization, which is monopoly power couple with anticompetitive practices, but it also prohibits various practices from companies that do not have monopoly power.

For example the Sherman Act prohibits attempted monopolization. You run afoul of that for anticompetitive conduct and a specific intent to monopolize if there is a dangerous probability that will achieve monopoly power.

The Clayton Act added restrictions on price discrimination, exclusive dealing, tying, and mergers and acquisitions that substantially reduce competition or tend to create monopolies.

[RobotToaster]

> You actually have to be a monopoly

Every person who shall monopolize, or attempt to monopolize, or combine or conspire with any other person or persons, to monopolize any part of the trade or commerce among the several States, or with foreign nations, shall be deemed guilty of a felony — Sherman Act, Section 2